A new filesystem aimed at sharing host filesystems with KVM guests, virtio-fs, was the
topic of a session led by Miklos Szeredi at the 2019 Linux Storage,
Filesystem, and Memory-Management Summit. The existing solution, which is
based on the 9P filesystem from Plan 9, has some
shortcomings, he said. Virtio-fs is a prototype that uses the Filesystem in
Userspace (FUSE) interface.

Source: LWN.net – [$] A filesystem for virtualization